Protesters calling for the release of Nigerian girls held a rally denouncing the police's ban on their daily protests.

Reuters: Afolabi Sotunde

Nigerian police say protesters are free to march in the country's capital after an uproar over comments by the commissioner which appeared to ban demonstrations over more than 200 schoolgirls kidnapped by rebels.

Joseph Mbu made a statement on Monday in which he appeared to forbid protests on grounds that they could be hijacked by "dangerous elements" who could threaten state security.

Protesters said they would challenge the ban in court and they filed a complaint.

But a statement from police spokesman Frank Mba on Tuesday said the commissioner had only meant to advise against gatherings because of intelligence that there was "infiltration and hijack of otherwise innocuous and peaceful protests by some criminal elements having links with insurgents".

"The force has not issued any order banning peaceful assemblies/protests anywhere in Nigeria," Mr Mba said.

"However... citizens are strongly advised to reconsider their positions on the issues of rallies and protests in FCT until the existing threats are appropriately neutralised," he said, referring to the Federal Capital Territory around Abuja.

Nigerian authorities argue they face an unenviable dilemma: if they try to free the girls, they risk some getting killed, or if they offer money or a prisoner swap, this would only leave the rebels stronger, endangering more lives in the long run.

A reluctance to pursue either strategy has created a stalemate, officials say.